Such adaptors are available in very different configurations and comprise two discrete parts. The part mounted at the forward region of the sighting telescope generally includes a clamp on which a pivot lug is disposed. A further discrete part of the adaptor is attached to a region of the sighting telescope which lies farther toward the rear. This part generally has a movable fixing element for releasably assembling the sighting telescope on the weapon.
It is a disadvantage that a clamp applies a significant force to the forward part of the sighting telescope thereby inducing stresses in the forward lenses of the sighting telescope when the assembly is conducted in an unskilled manner. Furthermore, the attachment of both parts of the adaptor must take place so as to be matched to each other as well as being matched to the weapon. This causes a difficult alignment during assembly with alignment errors occurring because of a skewed position of the optical axis of the sighting telescope with respect to the bore axis of the barrel of the weapon.
U.S. Pat. No. 4,959,908 discloses an attachment arrangement for attaching a sighting telescope to an intermediate piece with the sighting telescope being attached with a rail to an intermediate piece having a wedge-shaped cross section. This patent makes no disclosure with respect to the attachment of the intermediate piece to the weapon and the specific configuration of the intermediate piece.